First report of Rhizoctonia solani AG-2-2 IIIB causing Rice sheath blight in China.

Rice (Oryza sativa) is an important crop worldwide, rice is susceptible to many pathogens, one of the most significant being Rice Sheath Blight, caused by Rhizoctonia solani. This disease initially produces cloudy spots on the leaf sheaths and later affects grain filling, resulting in yield losses of over 45%（Chen et al. 2013） when severe. In many southern rice-growing areas of China, the impact of this disease has risen to become the most damaging of the three major rice diseases (Margani et al. 2018). In July 2023, In Yongfu County, Guangxi (110.022°E, 25.010°N), symptoms of rice sheath blight were observed. The leaf sheaths were affected, with small, water-soaked, dark green spots with indistinct edges appearing near the water surface. These spots gradually expanded into elliptical or cloud-like lesions. Eventually, the center of the lesions turned straw-yellow to grayish-white, while the edges turned brown to dark brown. Often, several lesions merged into large cloud-like patches. Fifteen symptomatic sheaths were collected disinfecting pieces of necrotic tissue with 3% NaClO for 1.5 minutes, followed by 75% alcohol for 1 minute. The pieces were then rinsed with sterile distilled water, subsequently plated on Potato Dextrose Agar in Petri dishes, and incubated at 28°C in the dark. One isolate was obtained from each diseased plant using the hyphal tip method. (Feng et al. 2008). Isolates were obtained and displayed initially white mycelium and gradually turned brown after three to four days. Septate hyphae were 4.27 to 10.73 µ m (average 6.41 µ m) in diameter and branched at Right angle or acute angle with a constriction at the origin of the branch point. Staining with 1% safranin O and 3% KOH solution (Bandoni 1979) revealed multinucleated cells (three to nine nuclei per cell, n = 144). In summary, these characteristics were consistent with the description of Rhizoctonia solani Kühn (Meyer et al. 1990). The anastomosis group (AG) was confirmed by selecting three representative isolates (GL-Q-10, GL-Q-13, GL-Q-15) for molecular identification. The target DNA was extracted using Chelex-100. The internal transcribed spacer (ITS) region was amplified and sequenced with primers ITS1 and ITS4. The sequences were deposited in GenBank (ITS, PQ047154, PQ047150, and PQ047151 The base pairs are respectively 713bp, 715bp and 776bp, respectively). Upon searching GenBank, accession number MT385836 was found (Zhou et al. 2021), which has a similarity of 99.15% with PQ047154, 98.87% with PQ047150, and 99.30% with PQ047151. Phylogenetic tree analysis based on ITS sequences showed that the isolates clustered monophyletically with strains of R. solani AG-2-2 IIIB. The fusion group of the strain is verified by the shape and color of its mycelial growth on PDA at 35°C, enabling the distinct differentiation of AG-2-2 IIIB from AG-2-2 IV in terms of both morphology and coloration.（Aktaruzzaman et al. 2019） Pathogenicity tests involved culturing the pathogenic bacteria on PDA for 7-10 days, Then, 10 healthy rice plants (greenhouse potted rice variety Dian Heyou 615) were selected at the heading stage, and 5 plants were inoculated on the leaf sheaths with 5 strains of 5 mm fungus cake with pathogenic bacteria and 5 plants without pathogenic bacteria (The rice soil was disinfected), wrapped in cotton for moisture retention. All plants were sealed in transparent plastic bags and incubated in a greenhouse at 30 °C for 7-15 days, with daily moisturizing using sterile distilled water (Humidity control at 70%). Seven days postinoculation, Those containing pathogenic bacteria have symptoms of rice sheath blight, No symptoms were detected on control plants. Rhizoctonia solani AG-2-2 IIIB was re-isolated from the inoculated plants as previously described, thus fulfilling Koch's postulates. The pathogenicity tests were repeated three times. At present, Rhizoctonia solani AG-2-2 IIIB is primarily pathogenic in plants such as sugar beet and beans. It has only been reported in Japan and other countries to cause rice disease (Engelkes et al. 1996; Kenji Inagaki et al. 2004), and Rhizoctonia solani AG-2-2 IIIB has never been reported in China to cause disease in rice. To our knowledge, this study is the first to identify Rhizoctonia solani AG-2-2 IIIB causing rice sheath blight in China. This finding will aid further research on rice sheath blight defense strategies and contribute to the development of better management practices for this disease.

Virome Analysis of Aconitum carmichaelii Reveals Infection by Eleven Viruses, including Two Potentially New Species.

Aconitum carmichaelii is a herbaceous herb indigenous to China that has been cultivated for traditional medicine for centuries. Virus-like symptoms of A. carmichaelii plants were observed on leaves in some A. carmichaelii plantations in Zhanyi and Wuding Counties, Yunnan Province, southwest China. High-throughput sequencing (HTS) was performed on 28 symptomatic plants, and the results revealed infection with 11 viruses, including 2 novel viruses and 9 previously described viruses: Aconitum amalgavirus 1 (AcoAV-1), aconite virus A (AcVA), cucumber mosaic virus (CMV), currant latent virus (CuLV), apple stem grooving virus (ASGV), chilli veinal mottle virus (ChiVMV), tomato spotted wilt orthotospovirus (TSWV), tobacco vein distorting virus (TVDV), and potato leafroll virus (PLRV). Two novel viruses tentatively named Aconitum potyvirus 1 and Aconitum betapartitivirus 1, were supported by sequence and phylogenetic analysis results of their genomes. We proposed the names Potyvirus aconiti and Betapartitivirus aconiti. RT-PCR assays of 142 plants revealed the predominance and widespread distribution of CMV, AcVA, and AcoPV-1 in plantations. The detection of isolates of CuLV, ASGV, ChiVMV, TSWV, TVDV, and PLRV infections for the first time in A. carmichaelii expands their known host ranges.

Dual RNA sequencing of Helicobacter pylori and host cell transcriptomes reveals ontologically distinct host-pathogen interaction.

Helicobacter pylori is a highly successful pathogen that poses a substantial threat to human health. However, the dynamic interaction between H. pylori and the human gastric epithelium has not been fully investigated. In this study, using dual RNA sequencing technology, we characterized a cytotoxin-associated gene A (cagA)-modulated bacterial adaption strategy by enhancing the expression of ATP-binding cassette transporter-related genes, metQ and HP_0888, upon coculturing with human gastric epithelial cells. We observed a general repression of electron transport-associated genes by cagA, leading to the activation of oxidative phosphorylation. Temporal profiling of host mRNA signatures revealed the downregulation of multiple splicing regulators due to bacterial infection, resulting in aberrant pre-mRNA splicing of functional genes involved in the cell cycle process in response to H. pylori infection. Moreover, we demonstrated a protective effect of gastric H. pylori colonization against chronic dextran sulfate sodium (DSS)-induced colitis. Mechanistically, we identified a cluster of propionic and butyric acid-producing bacteria, Muribaculaceae, selectively enriched in the colons of H. pylori-pre-colonized mice, which may contribute to the restoration of intestinal barrier function damaged by DSS treatment. Collectively, this study presents the first dual-transcriptome analysis of H. pylori during its dynamic interaction with gastric epithelial cells and provides new insights into strategies through which H. pylori promotes infection and pathogenesis in the human gastric epithelium. IMPORTANCE: Simultaneous profiling of the dynamic interaction between Helicobacter pylori and the human gastric epithelium represents a novel strategy for identifying regulatory responses that drive pathogenesis. This study presents the first dual-transcriptome analysis of H. pylori when cocultured with gastric epithelial cells, revealing a bacterial adaptation strategy and a general repression of electron transportation-associated genes, both of which were modulated by cytotoxin-associated gene A (cagA). Temporal profiling of host mRNA signatures dissected the aberrant pre-mRNA splicing of functional genes involved in the cell cycle process in response to H. pylori infection. We demonstrated a protective effect of gastric H. pylori colonization against chronic DSS-induced colitis through both in vitro and in vivo experiments. These findings significantly enhance our understanding of how H. pylori promotes infection and pathogenesis in the human gastric epithelium and provide evidence to identify targets for antimicrobial therapies.

Faecal microbiome and metabolic signatures in rectal neuroendocrine tumors.

Background: The prevalence of rectal neuroendocrine tumors (RNET) has increased substantially over the past decades. Little is known on mechanistic alteration in the pathogenesis of such disease. We postulate that perturbations of human gut microbiome-metabolome interface influentially affect the development of RNET. The study aims to characterize the composition and function of faecal microbiome and metabolites in RNET individuals. Methods: We performed deep shotgun metagenomic sequencing and untargeted liquid chromatography-mass spectrometry (LC-MS) metabolomic profiling of faecal samples from the discovery cohort (18 RNET patients, 40 controls), and validated the microbiome and metabolite-based classifiers in an independent cohort (15 RNET participants, 19 controls). Results: We uncovered a dysbiotic gut ecological microenvironment in RNET patients, characterized by aberrant depletion and attenuated connection of microbial species, and abnormally aggregated lipids and lipid-like molecules. Functional characterization based on our in-house and Human Project Unified Metabolic Analysis Network 2 (HUMAnN2) pipelines further indicated a nutrient deficient gut microenvironment in RNET individuals, evidenced by diminished activities such as energy metabolism, vitamin biosynthesis and transportation. By integrating these data, we revealed 291 robust associations between representative differentially abundant taxonomic species and metabolites, indicating a tight interaction of gut microbiome with metabolites in RNET pathogenesis. Finally, we identified a cluster of gut microbiome and metabolite-based signatures, and replicated them in an independent cohort, showing accurate prediction of such neoplasm from healthy people. Conclusions: Our current study is the first to comprehensively characterize the perturbed interface of gut microbiome and metabolites in RNET patients, which may provide promising targets for microbiome-based diagnostics and therapies for this disorder.

Complete mitochondrial genome of Rhipicephalus simus.

In this study, we report the basic characteristics of the Rhipicephalus simus mitochondrial genome, including structural organization and base composition of the rRNAs, tRNAs and protein-coding genes. The total length of the mitogenome was 14,929 bp, included 37 genes and with a genome structure similar to other ticks.